[PATCH V2] ARM: BCM5301X: Implement SMP support
Rafał Miłecki
zajec5 at gmail.com
Sun Mar 22 06:20:15 PDT 2015
Signed-off-by: Rafał Miłecki <zajec5 at gmail.com>
---
V2: Change code after receiving Florian's comments:
1) Use "mmio-sram"
2) Remove commented out ASM call
3) Fix coding style in ASM
4) Simplify finding OF node
---
Documentation/devicetree/bindings/arm/bcm4708.txt | 24 ++++
Documentation/devicetree/bindings/arm/cpus.txt | 1 +
arch/arm/boot/dts/bcm4708.dtsi | 13 ++
arch/arm/mach-bcm/Makefile | 3 +
arch/arm/mach-bcm/bcm5301x_headsmp.S | 45 ++++++
arch/arm/mach-bcm/bcm5301x_smp.c | 158 ++++++++++++++++++++++
6 files changed, 244 insertions(+)
create mode 100644 arch/arm/mach-bcm/bcm5301x_headsmp.S
create mode 100644 arch/arm/mach-bcm/bcm5301x_smp.c
diff --git a/Documentation/devicetree/bindings/arm/bcm4708.txt b/Documentation/devicetree/bindings/arm/bcm4708.txt
index 6b0f49f..3dd0e9d 100644
--- a/Documentation/devicetree/bindings/arm/bcm4708.txt
+++ b/Documentation/devicetree/bindings/arm/bcm4708.txt
@@ -6,3 +6,27 @@ Boards with the BCM4708 SoC shall have the following properties:
Required root node property:
compatible = "brcm,bcm4708";
+
+Optional sub-node properties:
+
+compatible = "mmio-sram" for SRAM access with IO memory region
+ This is needed for SMP-capable SoCs which use part of
+ SRAM for storing location of code to be executed by the
+ extra cores.
+ SMP support requires another sub-node with compatible
+ property "brcm,bcm4708-sysram".
+
+Example:
+
+ sysram at ffff0000 {
+ compatible = "mmio-sram";
+ reg = <0xffff0000 0x10000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0 0xffff0000 0x10000>;
+
+ smp-sysram at 0 {
+ compatible = "brcm,bcm4708-sysram";
+ reg = <0x0 0x1000>;
+ };
+ };
diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
index 6aa331d..3507ae3 100644
--- a/Documentation/devicetree/bindings/arm/cpus.txt
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -189,6 +189,7 @@ nodes to be present and contain the properties described below.
can be one of:
"allwinner,sun6i-a31"
"arm,psci"
+ "brcm,bcm4708-smp"
"brcm,brahma-b15"
"marvell,armada-375-smp"
"marvell,armada-380-smp"
diff --git a/arch/arm/boot/dts/bcm4708.dtsi b/arch/arm/boot/dts/bcm4708.dtsi
index 31141e8..c0af5cc 100644
--- a/arch/arm/boot/dts/bcm4708.dtsi
+++ b/arch/arm/boot/dts/bcm4708.dtsi
@@ -15,6 +15,7 @@
cpus {
#address-cells = <1>;
#size-cells = <0>;
+ enable-method = "brcm,bcm4708-smp";
cpu at 0 {
device_type = "cpu";
@@ -31,4 +32,16 @@
};
};
+ sysram at ffff0000 {
+ compatible = "mmio-sram";
+ reg = <0xffff0000 0x10000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0 0xffff0000 0x10000>;
+
+ smp-sysram at 0 {
+ compatible = "brcm,bcm4708-sysram";
+ reg = <0x0 0x1000>;
+ };
+ };
};
diff --git a/arch/arm/mach-bcm/Makefile b/arch/arm/mach-bcm/Makefile
index 4c38674..ca12727 100644
--- a/arch/arm/mach-bcm/Makefile
+++ b/arch/arm/mach-bcm/Makefile
@@ -36,6 +36,9 @@ obj-$(CONFIG_ARCH_BCM2835) += board_bcm2835.o
# BCM5301X
obj-$(CONFIG_ARCH_BCM_5301X) += bcm_5301x.o
+ifeq ($(CONFIG_SMP),y)
+obj-$(CONFIG_ARCH_BCM_5301X) += bcm5301x_smp.o bcm5301x_headsmp.o
+endif
# BCM63XXx
obj-$(CONFIG_ARCH_BCM_63XX) := bcm63xx.o
diff --git a/arch/arm/mach-bcm/bcm5301x_headsmp.S b/arch/arm/mach-bcm/bcm5301x_headsmp.S
new file mode 100644
index 0000000..9ca8d20
--- /dev/null
+++ b/arch/arm/mach-bcm/bcm5301x_headsmp.S
@@ -0,0 +1,45 @@
+/*
+ * Broadcom BCM470X / BCM5301X ARM platform code.
+ *
+ * Copyright (c) 2003 ARM Limited
+ * All Rights Reserved
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+#include <linux/linkage.h>
+
+/*
+ * BCM5301X specific entry point for secondary CPUs.
+ */
+ENTRY(bcm5301x_secondary_startup)
+ mrc p15, 0, r0, c0, c0, 5
+ and r0, r0, #15
+ adr r4, 1f
+ ldmia r4, {r5, r6}
+ sub r4, r4, r5
+ add r6, r6, r4
+pen: ldr r7, [r6]
+ cmp r7, r0
+ bne pen
+
+ /*
+ * In case L1 cache has unpredictable contents at power-up
+ * clean its contents without flushing.
+ */
+ bl v7_invalidate_l1
+
+ mov r0, #0
+ mcr p15, 0, r0, c7, c5, 0 /* Invalidate icache */
+ dsb
+ isb
+
+ /*
+ * we've been released from the holding pen: secondary_stack
+ * should now contain the SVC stack for this core
+ */
+ b secondary_startup
+ENDPROC(bcm5301x_secondary_startup)
+
+ .align 2
+1: .long .
+ .long pen_release
diff --git a/arch/arm/mach-bcm/bcm5301x_smp.c b/arch/arm/mach-bcm/bcm5301x_smp.c
new file mode 100644
index 0000000..45d7089
--- /dev/null
+++ b/arch/arm/mach-bcm/bcm5301x_smp.c
@@ -0,0 +1,158 @@
+/*
+ * Broadcom BCM470X / BCM5301X ARM platform code.
+ *
+ * Copyright (C) 2002 ARM Ltd.
+ * Copyright (C) 2015 Rafał Miłecki <zajec5 at gmail.com>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include <asm/cacheflush.h>
+#include <asm/delay.h>
+#include <asm/smp_plat.h>
+#include <asm/smp_scu.h>
+
+#include <linux/clockchips.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#define SOC_ROM_LUT_OFF 0x400
+
+extern void bcm5301x_secondary_startup(void);
+
+static void __cpuinit write_pen_release(int val)
+{
+ pen_release = val;
+ smp_wmb();
+ sync_cache_w(&pen_release);
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+static void __init bcm5301x_smp_secondary_set_entry(void (*entry_point)(void))
+{
+ void __iomem *sysram_base_addr = NULL;
+ struct device_node *node;
+
+ node = of_find_compatible_node(NULL, NULL, "brcm,bcm4708-sysram");
+ if (!of_device_is_available(node))
+ return;
+
+ sysram_base_addr = of_iomap(node, 0);
+ if (!sysram_base_addr) {
+ pr_warn("Failed to map sysram\n");
+ return;
+ }
+
+ writel(virt_to_phys(entry_point), sysram_base_addr + SOC_ROM_LUT_OFF);
+
+ dsb_sev(); /* Exit WFI */
+ mb(); /* make sure write buffer is drained */
+
+ iounmap(sysram_base_addr);
+}
+
+static void __init bcm5301x_smp_prepare_cpus(unsigned int max_cpus)
+{
+ void __iomem *scu_base;
+
+ if (!scu_a9_has_base()) {
+ pr_warn("Unknown SCU base\n");
+ return;
+ }
+
+ scu_base = ioremap((phys_addr_t)scu_a9_get_base(), SZ_256);
+ if (!scu_base) {
+ pr_err("Failed to remap SCU\n");
+ return;
+ }
+
+ /* Initialise the SCU */
+ scu_enable(scu_base);
+
+ /* Let CPUs know where to start */
+ bcm5301x_smp_secondary_set_entry(bcm5301x_secondary_startup);
+
+ iounmap(scu_base);
+}
+
+static void __cpuinit bcm5301x_smp_secondary_init(unsigned int cpu)
+{
+ trace_hardirqs_off();
+
+ /*
+ * let the primary processor know we're out of the
+ * pen, then head off into the C entry point
+ */
+ write_pen_release(-1);
+
+ /*
+ * Synchronise with the boot thread.
+ */
+ spin_lock(&boot_lock);
+ spin_unlock(&boot_lock);
+}
+
+static int __cpuinit bcm5301x_smp_boot_secondary(unsigned int cpu,
+ struct task_struct *idle)
+{
+ unsigned long timeout;
+
+ /*
+ * set synchronisation state between this boot processor
+ * and the secondary one
+ */
+ spin_lock(&boot_lock);
+
+ /*
+ * The secondary processor is waiting to be released from
+ * the holding pen - release it, then wait for it to flag
+ * that it has been released by resetting pen_release.
+ *
+ * Note that "pen_release" is the hardware CPU ID, whereas
+ * "cpu" is Linux's internal ID.
+ */
+ write_pen_release(cpu_logical_map(cpu));
+
+ /* Send the secondary CPU SEV */
+ dsb_sev();
+
+ udelay(100);
+
+ /*
+ * Send the secondary CPU a soft interrupt, thereby causing
+ * the boot monitor to read the system wide flags register,
+ * and branch to the address found there.
+ */
+ arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+
+ /*
+ * Timeout set on purpose in jiffies so that on slow processors
+ * that must also have low HZ it will wait longer.
+ */
+ timeout = jiffies + (HZ * 10);
+ while (time_before(jiffies, timeout)) {
+ smp_rmb();
+ if (pen_release == -1)
+ break;
+
+ udelay(10);
+ }
+
+ /*
+ * now the secondary core is starting up let it run its
+ * calibrations, then wait for it to finish
+ */
+ spin_unlock(&boot_lock);
+
+ return pen_release != -1 ? -ENOSYS : 0;
+}
+
+static struct smp_operations bcm5301x_smp_ops __initdata = {
+ .smp_prepare_cpus = bcm5301x_smp_prepare_cpus,
+ .smp_secondary_init = bcm5301x_smp_secondary_init,
+ .smp_boot_secondary = bcm5301x_smp_boot_secondary,
+};
+
+CPU_METHOD_OF_DECLARE(bcm5301x_smp, "brcm,bcm4708-smp",
+ &bcm5301x_smp_ops);
--
1.8.4.5
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